Prenatal cocaine alters normoxic sleep-wake and diaphragmatic EMG patterns in piglets.
This study assessed in piglets the effects of prenatal cocaine administration on sleep-wake states (SWS) and respiratory parameters, utilizing diaphragmatic electromyogram (EMGdi) recordings during normoxia before and after hypoxia (0.10 F(I,O2), 10 min). We asked whether the respiratory effects were linked to a specific SWS, and whether there was a difference in respiratory measures between the two normoxic conditions. Unsedated, chronically instrumented 3-9- or 21-31-day-old piglets, representing distinct stages in developmental respiratory control, were used. In pre-hypoxic normoxia, prenatal cocaine enhanced sleep at the expense of wakefulness and increased EMGdi amplitude, slope, and area in both age groups regardless of SWS; after the hypoxia, the respiratory findings persisted in the young group, but disappeared in the older group [corrected]. In the young group and regardless of SWS, interbreath interval (ttot) and expiratory duration (ttot - tEMGdi[duration of EMGdi]) were shorter in the cocaine-exposed than in the unexposed piglets, and ttot, tEMGdi, and (ttot - tEMGdi) decreased from pre- to post-hypoxic normoxia. In the older group, ttot and (ttot - tEMGdi) differed among SWS, but were unaffected by drug treatment; tEMGdi was higher with cocaine exposure in pre-, but not in post-hypoxic normoxia, and two-thirds of the EMGdi measurements during post-hypoxic normoxia exhibited a similar magnitude in the drug-treated and untreated groups regardless of SWS. We conclude that 1) prenatal cocaine alters both SWS and EMGdi, but the EMGdi effects are independent of SWS; and 2) the similar EMGdi patterns in the older group after hypoxia, regardless of drug treatment, suggest that hypoxia and chronic prenatal cocaine might alter EMGdi by similar mechanisms.
Moss
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IR
Department of Pediatrics, McGill University, Montreal, Quebec, Canada.
Laferrière
A
A
D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D003042:Cocaine / Q000008:administration & dosage*; D003964:Diaphragm / Q000187:drug effects* / Q000502:physiology; D004195:Disease Models, Animal; D004576:Electromyography / Q000187:drug effects*; D005260:Female; D010100:Oxygen / Q000097:blood*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D015656:Respiratory Mechanics / Q000187:drug effects*; D012894:Sleep Stages / Q000187:drug effects*; D013552:Swine
D003042:Cocaine; D010100:Oxygen